With an energy crisis due to the depletion of petroleum resources, efforts are being made to develop energy resources replacing fossil fuels all around the world. As a part of such efforts, research for developing biofuels and biochemical materials which can replace fossil fuels with biomass to turn into a sustainable carbon economy and change a conventional chemical process into an environmentally-friendly bioprocess. The bioprocess is a new industry sector that can shift paradigm for upstream & downstream industries, and reduce a green house gas and a waste product.
As biomass for producing biofuels, the first-generation sugar-based biomass such as corn and sugarcane was changed into the second-generation lignocellulosic biomass, and recently the third-generation algae-based biomass is in the spotlight.
Among the algae-based biomass, red algae such as Gelidium amansii is known to have a higher carbohydrate content than those of green and brown algae, and agarose, which is the main polysaccharide constituting the red algae, is a polymer of 3,6-anhydro-L-galactose and D-galactose. The D-galactose is a fermentable monosaccharide that can be easily used by a microorganism, and has been widely studied to produce bioethanol by fermenting the D-galactose produced with a microorganism by hydrolyzing red algae biomass by a chemical or enzymatic treatment. Recently, an enzyme converting 3,6-anhydro-L-galactose was identified from microorganisms degrading agarose such as Saccharophagus degradans 2-40 and Pseudoalteromonas atlantica T6c (PCT/KR2012/000607). In addition, since a genomic sequence of Vibrio sp. EJY3, which is a microorganism capable of metabolizing 3,6-anhydro-L-galactose, known as a non-fermentable rare sugar, as a carbon source, is identified, a 3,6-anhydro-L-galactose metabolism-associated gene of the strains and a function of the gene are also being identified.
Research on a method of producing 3,6-anhydro-L-galactose and its function (Yun E J, et al. Process Biochem. (2011) 46(1):88-93. Yun E J, et al. Appl. Microbiol. Biotechnol. (2013) 97(7): 2961-70) has been reported by the inventors. For example, a reducing end of the 3,6-anhydro-L-galactose is easily hydrated, and thus exhibits a moisturizing function. Also, it was identified that the 3,6-anhydro-L-galactose has skin whitening and antioxidizing functions, and also has an effect of preventing colon cancer (Yun E J, et al. Appl. Microbiol. Biotechnol. (2013) 97(7): 2961-70).
However, the 3,6-anhydro-L-galactose is known as a non-fermentable monosaccharide that cannot be generally used by a microorganism, and, even though about 60% of red algae biomass consists of carbohydrates, it serves as the main reason of a low yield of biofuels from the of red algae biomass.